Psychophysical stress disturbs expression of mitochondrial biogenesis markers in hypothalamus and adenohypophysis

Summary. Although psychophysical stress is widespread in human society and a major contributor to a range of pathological conditions, it is not known if this form of stress regulates mitochondrial biogenesis in the hypothalamus or adenohypophysis, the main organs involved in compensatory specifc response of the organism to stress (so called “fght or flight” response). Accordingly, this study was designed to evaluate the effects of acute and repeated psychophysical stress on a profle of mitochondrial biogenesis markers in the hypothalamus and adenohypophysis. Rats were either lef undisturbed (freely moving, control group) or exposed to psychophysical stress by immobilization (IMO) for 2 h (acute, 1xIMO) or 2 h daily for 2 (repeated, 2xIMO) or 10 consecutive days (repeated, 10xIMO). Result suggest that all types of immobilization stress signifcantly increase expression of hypothalamic NRF1 (nuclear respiratory factor 1; acts on the genes for subunits of the OXPHOS encoded by the nuclear genome) as well as its downstream target TFAM (mitochondrial transcription factor A), the essential ubiquitous factors for mtDNA replication and expression. In the same samples, TFB1M (markedly enhance mtDNA transcription) significantly decreased, while the level of COX4 (mitochondrial complex IV cytochrome C oxidase) protein was reduced only in hypothalamuses isolated from repeatedly stressed rats. Independently of the type of stress, the level of PGC1 protein, the master regulator of mitochondrial biogenesis involved in transcriptional control of all processes related to mitochondrial homeostasis and integrator of environmental signals, remained unchanged. In adenohypophyses of the same animals, 10xIMO signifcantly increased expression of adenohypophyseal PGC1 as well as its downstream target TFB1M, while NRF1 and TFAM remained unchanged. Similarly to hypothalamuses, the level of COX4 protein was reduced in adenohypophyses isolated from repeatedly stressed rats. Our results provide new molecular insights into the relationship between stress and hypothalamo-adenohypophyseal axis, as well as mitochondrial biology

Mitochondrial Dynamics Markers and Related Signaling Molecules Are Important Regulators of Spermatozoa Number and Functionality

Here, we study possible mechanisms of (in/sub)fertility related to the acute or repeated psychological stresses (the most common stresses in human society) by following the transcriptional profile of 22 mitochondrial dynamics/function markers and 22 signaling molecules regulating both mitochondrial dynamics and spermatozoa number/functionality. An in vivo study mimicking acute (once for 3 h) and repeated (3 h for 10 consecutive days) psychophysical stress was performed on adult rats. The analysis of hormones, the number/functionality of spermatozoa, and 44 transcriptional markers were performed on individual samples from up to 12 animals per group. Results showed that both types of stress reduced spermatozoa functionality (acute by 4.4-fold, repeated by 3.3-fold) and ATP production (acute by 2.3-fold, repeated by 14.5-fold), while only repeated stress reduces the number of spermatozoa (1.9-fold). Stress significantly disturbed transcription of 34-out-of-44 markers (77%). Mitochondrial dynamics and functionality markers: 18-out-of-22 =>82% (mitochondrial-biogenesis-markers –>6-out-of-8 =>75%; mitochondrial-fusion-markers –>3-out-of-3 =>100%; mitochondrial-fission-markers –>1-out-of-2 =>50%; mitochondrial-autophagy-markers –>3-out-of-3 =>100%; mitochondrial-functionality-markers –>5-out-of-6 =>83%). Markers of signaling pathways regulating both mitochondrial dynamics/functionality and spermatozoa number/functionality important for male (in/sub)fertility –>16-out-of-22 =>73% (cAMP-signaling-markers –>8-out-of-12 =>67%; MAPK-signaling-markers –>8-out-of-10 =>80%). Accordingly, stress-triggered changes of transcriptional profile of mitochondrial dynamics/functionality markers as well as signaling molecules regulating both mitochondrial dynamics and spermatozoa number and functionality represent adaptive mechanisms

Insulin/IGF1 signalling regulates the mitochondrial biogenesis markers in steroidogenic cells of prepubertal testis, but not ovary

Controlled changes in mitochondrial biogenesis and morphology are required for cell survival and homeostasis, but the molecular mechanisms are largely unknown. Here, male and female prepubertal mice (P21) with insulin and IGF1 receptors deletions in steroidogenic tissues (Insr/Igf1r-DKO) were used to investigate transcription of the key regulators of mitochondrial biogenesis (Ppargc1a, Ppargc1b, Pparg, Nrf1, Tfam) and architecture (Opa1, Mfn1, Mfn2) in Leydig cells, ovaries and adrenals. Results showed that the expression of PGC1, a master regulator of mitochondrial biogenesis and integrator of environmental signals, and its downstream target Tfam, significantly decreased in androgen-producing Leydig cells. This is followed by reduction of Mtnd1, an mtDNA encoded transcript whose core subunit belongs to the minimal assembly required for catalysis. The same markers remained unchanged in ovaries. In contrast, in adrenals, the pattern of transcripts for mitochondrial biogenesis markers was the same in both sexes, but opposite from that observed in Leydig cells. The level of transcripts for markers of mitochondrial architecture (Mfn1, Mfn2) significantly increased in Leydig cells from Insr/Igf1r-DKO, but not in ovaries. This was followed by mitochondrial morphology disturbance, suggesting that the mitochondrial phase of steroidogenesis could be affected. Indeed, basal and pregnenolone stimulated progesterone productions in the mitochondria of Leydig cells from Insr/Igf1r-DKO decreased more than androgen production, and were barely detectable. Our results are the first to show that INSR and IGF1R are important for mitochondrial biogenesis in gonadal steroidogenic cells of prepubertal males, but not females and they serve as important regulators of mitochondrial architecture and biogenesis markers in Leydig cells

Spermatozoal Mitochondrial Dynamics Markers and Other Functionality-Related Signaling Molecules Exert Circadian-like Response to Repeated Stress of Whole Organism

In the search for the possible role of the mitochondrial dynamics markers in spermatozoa adaptation, an in vivo approach was designed to mimic situations in which human populations are exposed to 3 h of repeated psychological stress (the most common stress in human society) at different time points during the day (24 h). The hormones (stress hormone corticosterone and testosterone), the number and the functionality of spermatozoa (response to acrosome-reaction-inducer progesterone), as well as the transcriptional profiles of 22 mitochondrial dynamics and function markers and 22 signaling molecules regulating both mitochondrial dynamics and spermatozoa number and functionality were followed at three time points (ZT3, ZT11, and ZT23). The results show that repeated stress significantly decreased the number and functionality of spermatozoa at all time points. In the same samples, the transcriptional profiles of 91% (20/22) of mitochondrial dynamics and functionality markers and 86% (19/22) of signaling molecules were disturbed after repeated stress. It is important to point out that similar molecular changes in transcriptional profiles were observed at ZT3 and ZT23, but the opposite was observed at ZT11, suggesting the circadian nature of the adaptive response. The results of PCA analysis show the significant separation of repeated stress effects during the inactive/light and active/dark phases of the day, suggesting the circadian timing of molecular adaptations

Deficiency in insulin-like growth factors signalling in mouse Leydig cells increase conversion of testosterone to estradiol because of feminization

A growing body of evidence pointed correlation between insulin-resistance, testosterone level and infertility, but there is scarce information about mechanisms. The aim of this study was to identify the possible mechanism linking the insulin-resistance with testosterone-producing-Leydig-cells functionality